1. Field of the Invention
The invention relates to the protection of readable script formed on a face of an object such as an official document.
2. Description of the Related Art
In many applications, it is necessary for script formed earlier on objects to be protected against forgery and/or for the purpose of authentication and/or in order to guarantee its integrity.
One known solution (for example EP-0271941 or U.S. Pat. No. 5,232,527) consists in covering the readable script with a transparent film (that is to say a film making it possible to read the script that it covers) which adheres to the object and has a free outer face after having been placed on the object.
The object may, for example, be an official document (passport, visa, identity card, driver's license, bank card, access control card, passes, tags, judicial document, survey map, manufacturing schematic or other diagram, etc.) bearing readable script such as variable records (name, first name, address, photograph, etc. of a bearer or of the parties, etc.) and/or common records (security designs, registers, lists, field names, seals, holograms, etc.) to be protected against forgery and/or for the purpose of authentication and/or in order to guarantee its integrity (that is to say that it has not been tampered with or modified). The object may also be packaging, a product or article of any type bearing readable script which needs to be protected, such as text, a logo, drawing, photograph, serial number, etc.
Throughout the text, the term “readable script” will be used to mean any sign or pattern formed on the document, which can be read by a person at least under certain conditions (in particular under normal illumination with visible light; and/or under specific illumination; and/or after activating an electronic device (screen) or the like, etc.) which may be at least partially represented by recordable digital data. This may involve text (handwriting or printed characters); codes (ASCII, universal optoelectronically read codes such as barcodes, etc.); images or photographs, etc.
Integrated circuit memory devices (chips) are furthermore known which have a contactless information transmission link, in particular for reading, making it possible to associate personalized information securely with objects such as bank cards, electronic passes, electronic tags, etc. WO 02/21436 envisages the integration of a contactless chip with a document for identifying a physical individual, in particular when the document is being personalized, for example by integrating it in a security film or sandwiching it between laminated layers of the document. This document does not indicate how such a chip can be produced and does not explain how this contactless chip could in practice be integrated with a security film. Moreover in view of the thickness of such a chip, the problems linked to electrical connection of the integrated circuit with the associated antenna(s) and the prohibitive size of the antenna needed in order to obtain coupling with a reader at a sufficient range with respect to the space available on the document, the cited variant of integration with a security film is not practically viable in the light of this document.
Sandwiched incorporation of the chip between two sheets of the document is also expensive and poses practical manufacturing problems. There is in particular a risk that such a chip, which is relatively fragile, will not withstand the process of printing the personalization script. If it is associated with the document after this printing, such association is complex and not very reliable.
In any event, a chip incorporated with a document by sandwiching is physically disassociated from the readable script, so that tampering with the chip and with the readable script may be carried out independently.
It should also be noted that if a contactless chip and its antenna have small dimensions, this entails a short reading range. It is furthermore necessary to place the chip very precisely with respect to a reading device—in particular with respect to the axis of the antenna of this reading device.
Furthermore, FR-2 812 482 or EP-0826190 describe contactless devices having chip(s) with magnetic coupling between two antennas, one of which is an antenna coil electrically connected to the integrated circuit of the chip—in particular of the “coil on chip” type—and one is a passive antenna coil of larger dimensions, making it possible to increase the reading range of the chip with less bulk. The two antennas may be magnetically coupled by means of a coupling loop which is formed by the large coil, and whose dimensions correspond to those of the small coil. FR-2 812 482 mentions that the large coil may be incorporated in the thickness of the cover of a booklet, each page of which holds one or more contactless micromodule(s) (chip with its integrated antenna (small coil)) fixed on a plastic sheet arranged in a booklet. These devices do not provide a solution to the problem of protecting readable script effectively, in particular against forgery and/or for the purpose of authentication and/or in order to guarantee its integrity. In particular, the chips themselves are unprotected and may be corrupted or even replaced by a forger. Placing them on each page of the booklet is expensive and complicated, especially if coupling of the type described by EP-0826190 is envisaged. Furthermore, incorporating an antenna with large dimensions in the thickness of the cover is expensive and, since it makes this antenna invisible, does not allow precise subsequent positioning of each chip with respect to this antenna. Yet this precise positioning is indispensable in order to obtain sufficient magnetic coupling.
It should also be noted that the solution described in FR-2 812 482 does not in practice offer effective coupling of each individual antenna with the group antenna.
The prior art thus does not provide an economical, simple and reliable solution, compatible with practical implementation on an industrial scale, which makes it possible for an electronic memory device having microcircuit(s) with contactless reading, referred to as a contactless chip, to be associated effectively with an object bearing readable script, with a view to protecting this readable script.